The present invention relates to accessories for flexible support systems using elongated support members that vary in position to support planer and/or three-dimensional workpieces.
Numerous manufacturing processes require a means to support a workpiece, without causing damage, so that an operation can be effected thereon, particularly an operation which applies a force or pressure to the workpiece, such as a printed circuit board (PCB) during printing or population. The face of the workpiece to be supported may not necessarily be planer, as demonstrated by the example of a two-sided electronics assembly; at least one application requires tooling to support a three dimensional face.
There are several known apparatuses, which utilize elongated support members, which conform to the profile of the contact surface of the workpiece.
Thyberg et al. teach an apparatus using a multiplicity of hard balls and the application of pressure to the balls to provide a simple and effective locking mechanism. The elongated support members include ridges formed perpendicular to the axis of motion, whereby pressure (shown as by displacing the balls with an additional member) can be applied to the multiplicity of hard balls to effectively lock about the said ridges.
Frosch et al. teach a plurality of spindles (elongated support members) which contour to the workpiece and are secured in position using a locking piston associated with each spindle (or pair of spindles). The elongated support members are raised to the workpiece using springs.
Barozzi teaches a multiplicity of parallel pins in parallel rows which utilize friction to arrest the pins to the respective position. The frictional locking means consist of elastic elements interpositioned with elastic deformation between each of the parallel rows of pins. Barozzi utilizes flat springs located along parallel pins.
Dougherty et al. teach an anvil (plurality of elongated support members) having a uniquely configurable face where the elongated support members are raised by a fluid (air, fluid, or similar) directly contacting the pins. The pins are then retained against any downward force by a individual sleeves with slits that are placed about the shaft of the pins; the sleeves are compressed inwardly when under external pressure exerted by elastomeric tubes that enclosed the slit sleeves.
Puettmer, et al. teach a profiled clamping jaw, whereby the profiling process utilizes a fluid and individual needle valves to raise and hold the plurality of pins to a contour. The apparatus comprises of a complex system to individually move and hold each clamping ram (elongated support member) in position. The system does not allow the removal of any of the clamping rams.
Beale teaches an apparatus that provides support for a predetermined position raising and lowering only specified support members. Beale further teaches an apparatus which can secure a workpiece to a fixture using thin clamping foils which will not damage or interfere with the screen printing process.
Each of the above contouring support apparatuses is limited where they do not provide a means for easy removal or re-installation of any of the elongated support members.
The two parent applications disclose several apparatuses for supporting a workpiece using a plurality of elongated support members which adjust to conform to the profile of the surface of the workpiece to be supported.
The flexible, self-conforming workpiece support systems disclosed in the parent applications, as well as similar apparatuses such as the cited arts may be subjected to harsh environments such as solder printing. Solder paste, used during the solder printing process, is known to drop into the solder printing apparatus. The solder paste comprises of small (approximately 0.0008xe2x80x3 diameter) spheres of solder (tin lead) mixed in flux paste to a viscosity of approximately 1xc3x9710{circumflex over ( )}6 centipoise. When dried, the solder paste may have properties similar to clay or cement. The small particles of solder may act as abrasives.
The flexible, self conforming workpiece support systems disclosed in the parent applications, as well as similar apparatuses such as the cited arts may provide an upward force to the workpiece during the profiling process. This said upward force can cause the workpiece to flex upwards.
What is desired is a system which is flexible, can automatically create a profile to support the face of any workpiece, including a non-planer surface, and minimizes any forces transferred to the said face. The system should be designed to be repeatable, serviceable, and with minimal complexity. Further, the system should incorporate a method, features and or accessories to increase repeatability and reliability.
One aspect of the present invention is to provide a means to support one face of a workpiece to support the workpiece during an operation in which a force is applied to another face of the workpiece.
A second aspect of the present invention is to provide a means to support the workpiece using a plurality of elongated support members, whereby the plurality of elongated support members may create a profile of the contact face of the workpiece.
A third aspect of the present invention is to provide a, preferably automated, means to reset the elongated support members to the predetermined, xe2x80x9cmaximumxe2x80x9d distance from the primary assembly position, where the elongated support members are temporarily held in position by a resistive force. The elongated support members are adjusted to the desired height by bringing the workpiece and the primary assembly together, where the surface of the workpiece adjusts the elongated support members against a resistive force to the desired heights.
A fourth aspect of the present invention is to provide a holding force to hold the elongated support members after the elongated support members are positioned in the desired profile.
A fifth aspect of the present invention is the ability to easily remove or install any of the said support members from the primary assembly of the invention.
A sixth aspect of the present invention is a method to vary the size of the array of elongated support members to match the variety of subject workpieces.
A seventh aspect of the present invention is a method and apparatus to control the height of the support elongated support members to either in the maximum distance from the primary assembly or minimum distance from the primary assembly.
An eighth aspect of the present invention is an apparatus used to protect the shaft of the elongated support members from foreign objects such as solder paste.
A ninth aspect of the present invention is the inclusion of the protective member in a molded compliant member which slides over the top of the elongated support member.
A tenth aspect of the present invention is a method of temporarily reinforcing the workpiece to provide a planar top surface.
An eleventh aspect of the present invention is an apparatus for temporarily reinforcing the workpiece to provide a planar top surface.
A twelfth aspect of the present invention is the ability to automatically profile the plurality of elongates support members to the underside of the workpiece.
A thirteenth aspect of the present invention is the ability to use the same member to profile the plurality of pins to the one face of the workpiece as well as holding the plurality of pins to the profile against force(s) applied to the another face of the workpiece.
A fourteenth aspect of the present invention is the ability to raise the plurality of elongated support members using at least one of: springs, a reset plate in conjunction with a resistive member, or fluid.
A fifteenth aspect of the present invention is the inclusion of a single molded member to act as individual pistons to contour the plurality of elongated support members.
A sixteenth aspect of the present invention is the inclusion of a single member to seal each individual piston to maintain the contour of the plurality of elongated support members.
A seventeenth aspect of the present invention is the ability to limit the height of the individual pistons during the contouring process.
An eighteenth aspect of the present invention is the ability to retract the elongated support members by the removal of fluid.
A nineteenth aspect of the present invention is the inclusion of a means to individually identify each respective perforation for each respective elongated support member to identify a desired pattern for a particular workpiece.
The invention, a method and apparatus comprising:
A mechanism which can profile a plurality of elongated support members to a surface of an object. Several options are described herein, including springs, a resistive member (magnetic, frictional, or similar), and fluid in conjunction with a molded member.
A mechanism which can maintain the position of the elongated support members in a contoured position. Several options include a sliding single perforated plate to apply a clamping holding force, increasing the resistance force from a resistive member such as by increasing the magnetic force, and sealing a fluid within the above described molded member.
A mechanism of ensuring the planarity of the workpiece whereby the mechanism is placed against the workpiece, the second planar object can be a support block, stencil (and optional squeegee), and the like.
A protective member for protecting the shaft of the elongated support members and the openings in the apparatus from foreign materials such as solder paste. The member can be included in a molded compliant member and placed around or over the top of the elongated support members.
The elongated support members can optionally have a mechanism that that allows the elongated support member to be assembled into the primary assembly, while allowing the elongated support member to by removed as desired. Options include a xe2x80x9cC-clipxe2x80x9d, a rotating securing mechanism, a removable plate and the like.
The top surface of the apparatus can also be marked to identify the locations of each elongated support member individually as a means to provide an operator with a repeatable process for arrangement of installed/not-installed elongated support members.